Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

18. The Heart

Cardiac Cycle

Anatomy & Physiology

18. The Heart

Cardiac Cycle

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Problem 7

Textbook Question

Cardiac output is equal to the:
(a) Difference between the end-diastolic volume and the end-systolic volume
(b) Product of heart rate and stroke volume
(c) Difference between the stroke volume at rest and the stroke volume during exercise
(d) Stroke volume less the end-systolic volume
(e) Product of heart rate and blood pressure

Verified step by step guidance

Step 1: Understand the concept of cardiac output. Cardiac output (CO) is the volume of blood pumped by the heart per minute. It is a key measure of heart function and is influenced by heart rate (HR) and stroke volume (SV).

Step 2: Recall the formula for cardiac output. The correct formula is CO = HR × SV, where HR is the number of heartbeats per minute and SV is the volume of blood ejected by the heart in one beat.

Step 3: Analyze the options provided in the problem. Option (b) states that cardiac output is the product of heart rate and stroke volume, which matches the formula for cardiac output.

Step 4: Eliminate incorrect options by understanding their definitions. For example, (a) refers to the difference between end-diastolic volume (EDV) and end-systolic volume (ESV), which defines stroke volume, not cardiac output. Similarly, (e) involves blood pressure, which is not part of the cardiac output formula.

Step 5: Confirm that option (b) aligns with the definition and formula for cardiac output, making it the correct answer.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Cardiac Output

Cardiac output (CO) is a critical physiological measure that represents the volume of blood the heart pumps per minute. It is calculated by multiplying heart rate (HR) by stroke volume (SV), where stroke volume is the amount of blood ejected by the heart with each beat. Understanding CO is essential for assessing cardiovascular health and performance during various physical activities.

Heart Rate and Stroke Volume

Heart rate refers to the number of times the heart beats in one minute, while stroke volume is the amount of blood pumped by the heart in each contraction. Together, these two factors determine cardiac output. An increase in either heart rate or stroke volume can lead to an increase in cardiac output, which is vital during exercise or stress when the body requires more oxygen and nutrients.

End-Diastolic Volume and End-Systolic Volume

End-diastolic volume (EDV) is the volume of blood in the ventricles at the end of filling (diastole), while end-systolic volume (ESV) is the volume remaining in the ventricles after contraction (systole). The difference between EDV and ESV gives the stroke volume. Understanding these volumes is crucial for analyzing heart function and the efficiency of blood circulation.